Effect of Oral Beta-blocker Therapy on Microvolt T-wave Alternans

Category:  09 Signal Average ECG/T-Wave Alternans

Presentation Time: Thursday, 2:15 p.m. - 2:30 p.m.

Eran S. Zacks, MD, Daniel P. Morin, MD, Shaun Ageno, MD, Matthew Janik, MD, Daniel J. Cantillon, MD, Andreas C. Mauer, MD, Steven M. Markowitz, MD, Suneet Mittal, MD, Sei Iwai, MD, Bindi K. Shah, MD, Kenneth M. Stein, MD and Bruce B. Lerman, MD. Cornell University Medical Center, New York, NY

Presentation Number: AB14-4

Keyword: T-wave alternans, B-adrenergic receptor blockers

Background: T-wave alternans testing (TWA) has been proposed as a non-invasive method for risk stratification in pts with depressed LVEF. Prior investigation has shown that IV beta-blockers (BB) decrease the positivity rate of TWA in pts at electrophysiology study (EPS). The purpose of this study is to evaluate the influence of chronic oral BB on TWA.
Methods: We prospectively evaluated 251 pts with CAD, LVEF <40%, and NSVT (203 men, age 66.6 +/-10.5 yrs) who underwent EPS and were followed for > 2 yrs. TWA was performed using an atrial pacing protocol (CL:550 ms) and interpreted using standard criteria. The BB+ group was on oral BB at the time of EPS and the BB- group was off BB for >24 hrs. TWA positive and indeterminate results were grouped as non-negative based on prior convention. Follow-up for VT, VF, and death was obtained from chart review, device interrogation and social security death index. Sensitivity and specificity for TWA were calculated in the BB+ and BB- groups based on event-free 2-yr survival.
Results: The BB+ group had 210 (84%) pts and the BB- group had 41 (16%) pts. There were no significant differences between the two groups with regard to age, gender, LVEF, or ICD implant rate. The indeterminate rates for BB+ and BB- groups were comparable (28% vs. 27%, p=1.00). The BB+ and BB- groups had 144 (69%) pts and 28 (68%) pts with non-negative results respectively (p=1.00). There were 36 (17%) events in BB+ pts and 6 (15%) events in BB- pts (p=0.448). The sensitivities and specificities of TWA for 2-yr VT/VF-free survival did not differ significantly between the BB+ and BB- groups (sensitivity: 75% vs. 83%, p=0.557, specificity: 33% vs. 34%, p=0.503).
Conclusions: Chronic oral BB at the time of testing does not significantly influence the non-negative rate, sensitivity, and specificity of TWA. These findings suggest that there is no need to discontinue oral BB prior to TWA using an atrial pacing protocol.